Smart Use of Flash SSD — Finally

Everyone has no doubt gotten the word about today’s announcement from Isilon about their next-gen clustered NAS product line. If not, here are their talking points in a nutshell.

I. Isilon Continues to Deliver on its Long-Term Vision

a. Achieved profitability in Q4 ‘09
b. Record revenue and channel contribution in ‘09
c. Two new product lines released in March ’09 accounted for 50% of ’09 revenue
d. Nearly 1200 customers worldwide, with more than 260 new customers in ‘09

II. Isilon Capitalizes on Market Demand

a. Two out of every three customers in ’09 were non-Media & Entertainment
b. Rapid adoption in server virtualization, life sciences and government
c. North American channel grew from 25% of revenue in ‘08 to more than 55% in ‘09

Now, before you shrug this off as just so much more marketecture, let me tell you why I am following this company. (By the way, I have no financial relationship with them.)

First, everyone I am talking to right now seems to be interested in clustered NAS. Files are filling the junk drawer at a much faster rate than block/transaction data, making NAS a desirable storage solution. However, hanging out a lot of NAS mounts with no global namespace and no common management method is a pain. Hence, the world is looking for a good cluster/namespace story — of which there are precious few.

The cloud guys know this and are doing their best to beat NAS with NAS on steroids. Not sure how that will all work out, but I do know that the technology to actually cluster and namespace has been dragging its butt for years.

Isilon seems to have cracked the code. According to big customers, Microsoft, ARM, etc., they are delivering the bang expected from the buck. IBM just announced a competitor in SONAS, which builds on a less than successful technology called SOFAS (sp?). Snapshot-based backup via Tivoli is built in. We’ll see how that goes. Note that GX clustering and new/forthcoming ONTAP features in NetApp land are also supposed to compete in this space. However, if Isilon is to be believed, they are winning deals against NetApp after customers do some comparison testing.

Also, Isilon’s (and IBM’s) news has a kind of weird tie-in with developments with Dell and Exanet. Recall that Exanet burned through $70M of VC investment and went belly up. Dell is now picking over the carcass for less than what Exanet was asking them to invest to keep their company out of Chapter 7. Exanet was also trying to press forward a NAS clustering/global namespace play.

The other thing I like about Isilon is their use of Flash SSD. They are using it simply to store metadata about files parked in their clusters. That is not a hugely transactional use case, and it seems to me to be the first intelligent use of the technology that I’ve seen. Others have been proffering Flash as a database accelerator, but as I have argued here before, Flash SSD’s memory wear problems make it less appropriate for lots of changing data. I go for DRAM SSD for database acceleration, not Flash, otherwise I will probably be changing out the Flash drives every couple of hours/days/weeks depending on my workload. Kudos to Isilon for the first real-world application of Flash SSD that I have seen.

Still, it’s a shame that Isilon doesn’t offer their software as a standalone product. That way, I could use whatever storage I wanted.

The use of flash as a cache for metadata was also the goal of the NetApp PAM version I cards introduced in 2008. These were the 16GB DRAM variety and acted as a 2nd level CPU cache for ONTAP metadata and user data. The big ticket item – the biggest performance boost – came from the caching of metadata. Files data storage continues to grow, hence the 512GB flash-based PAM vII cards out now. Flash for metadata caching turns out to be a great use case. For NetApp, a good first step was investment in flash as cache.

To be clear, Isilon’s use of flash is not as a cache for meta-data. It differs from NetApp’s PAM implementation in that it is focused on accelerating UNCACHED meta-data access. The meta-data for OneFS lives permanently on the SSDs.

Caching meta-data operations is a no-brainer and is enabled in an Isilon system by its globally coherent DRAM-based cache, which expands as you add nodes into a system. DRAM is far lower latency than flash for cache.

The problem that we are specifically solving relates to uncached access, which occurs during treewalks, arbitrary directory/file access, first-access latency, and random I/O – all of which involve uncached meta-data lookups. The only solution to this problem is putting the meta-data on a faster medium.

Hi Jon,
It is SoFS (Scale-out File Services) that you were probably referring to. It was renamed to IBM Smart Business Storage Cloud as “SoFS” was misinterpreted as a file system, rather than a full customized storage solution.

SONAS is an integrated product ready-to-use, as opposed to Smart Business Storage Cloud which is customized with a set of service offerings.

The snapshots are independent of Tivoli, and appear as read-only subdirectories. Tivoli Storage Manager can be used to backup the original or snapshot files.

Thanks for the clarifications all. Now, Tony, two questions: what does a scale-out NAS solution for IBM mean for its relationship with NetApp, whose products the company resells? Second, what is the intent of announcing a hook for the product with the z/Linux mainframe OS? Are you thinking that companies will hang NAS off the back of mainframes? Will mainframes become big file servers at some point, in addition to their primary role in transactional processing? I would like to write something for z/Journal about this.